Method and apparatus for wrapping an article

ABSTRACT

An article to be wrapped such as a bundle of newspapers is firstly compressed so as to decrease its height, then it is moved forwardly in compressed state toward a sheet of thermoplastic resin film which is stretched tightly across the course of movement of the article so that the article is wrapped by the film from its forward end toward its rear end as the article continues its advancement. When the article is wrapped by the film over its upper and lower surfaces, it is stopped and the film portions at the rear of the article are fuse welded. Upon completion of the fuse welding, the film edges projecting transversely beyond the article are folded together and joined upon further advancement of the article.

Togashi et all.

[151 assess Fella, 22, 11972 [54] METUD AND APPARATUS A OM lAlPlPliN G AN Alit'lillClLlE [72] Inventors: Show Togashi; Yoshiflirna Malldjima, both of Kawasaki; llllruo 'llanallra; itaorn Narita,

[21] Appl. No; 35,699

3,327,449 6/1967 Hullhorst et al ..53/124 D X FOREIGN PATENTS OlR APPLlCATlONS 1,023,990 3/1966 Great Britain ..53/ 124 Primary Examiner-Travis S. McGehee Attorney-Shoemaker and Mattare 57 area An article to be wrapped such as a bundle of newspapers is firstly compressed so as to decrease its height, then it is moved forwardly in compressed state toward a sheet of thermoplastic resin film which is stretched tightly across the course of movement of the article so that the article is wrapped by the Film from its forward end toward its rear end as the article continues its advancement. When the article is wrapped by the film over its upper and lower surfaces, it is stopped and the film portions at the rear of the article are fuse welded. Upon completion of the fuse welding, the film edges projecting transversely beyond the article are folded together and joined upon further advancement of the article.

7 Claims, 417 Drawing Figures FIG. 32

:iiLDFEB 2 2 I972 SHEET 2 BF 8 INVENTORS SH 02 O TCGASHI YOSHINAO MAKIJIMA IMUO TANAKA 8 KAOIRU NARITA A ORNEYS SHEET 3 BF 8 IN VEN TORS l a wMAA KT 5 G Y M W 0 TN 1 0 M U WT O A H M SH Pmmrtam I972 3.63 396 sum 7 or INVENTOR9 SHOZO TOGASHI NA 8| KAORU NAR EJZAMJ W YOSHINAO KIJIMA IKUO ATTORNEY S METHOD AND APPARATUS FOR WRAPPING AN ARTICLE BACKGROUND OF THE INVENTION The present invention relates to a method for wrapping an article and more particularly to a method for wrapping an article with thermoplastic resin film under application of com pressive force around the article.

The present invention also relates to an apparatus to carry out the method.

The present invention is particularly applicable in wrapping a bundle of newspapers or the like when it is wrapped in a compressed state by a sheet of thermoplastic resin film, such as polyethylene film.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for wrapping an article such as a bundle of newspapers in a compressed state by a sheet of thermoplastic resin film.

A further object of the present invention is to provide a wrapping apparatus which firstly compresses an article to be wrapped and then wraps it with a sheet of thermoplastic resin film while the article is in a compressed state.

Another object of the present invention is to provide driving mechanisms especially useful in the apparatus according to the present invention for automatically adjusting the distance between one pair of conveyors parallel to the variation in distance between another pair of conveyors.

The method of wrapping an article according to the present invention comprises the steps of compressing the article, advancing the article in a compressed state toward a sheet of thermoplastic resin film which is tightly spread in front of the article transversely to the direction of movement of the article, wrapping the film around the article from its forward end toward its rear end in conjunction with its movement toward and past the film folding the rearward portions of the film adjacent the rear of the article, fuse welding together the folded portions of the film at the rearward surface of the article, severing the film at the fuse welded portion, and fold welding the film edges projecting transversely beyond the article as it continues to move forwardly.

The wrapping apparatus to carry out the method according to the present invention comprises means for feeding the article to be wrapped after compressing it, means for tightly spreading a sheet of thermoplastic resin film adjacent said article feeding means so that said film is caused to be drawn or stretched out consequent to the advance of the article to wrap the article from the forward end thereof toward the rear end, thereof means for fuse welding and severing the film portions left at the rear of the article as a result of the wrapping action, means for feeding the wrapped article further, and means for fuse welding the film edges projecting transversely beyond the article after folding them on both opposite side surfaces of the article,

In an embodiment of the wrapping apparatus according to the present invention, the apparatus is comprised of an entrance side pair of conveyors and an exit side pair of conveyors arranged in series, each pair comprising a top conveyor and a bottom conveyor with the distance between them being adjustable, means for tightly spreading a sheet of thermoplastic resin film vertically in a space between said two pairs of conveyors, means disposed in a space between said film spreading means and said exit side pair of conveyors for fuse welding the film portions at the rear of an article to be wrapped, two sets of guide plates arranged alongside said exit side pair of conveyors and means for fuse welding the edges of saidfilm projecting transversely beyond said article.

In one modification of the wrapping apparatus according to the ,present invention, in the wrapping apparatus just mentioned, a set of inserting levers are provided along each side of said exit side pair of conveyors, said levers respectively being adapted to be introduced between a space formed by said film edges projecting transversely beyond said article and moving at a speed slightly greater than that of said article when it is moved forwardly on said exit side pair of conveyors, whereby the forward end portion of said film is pulled or stretched forwardly so that said film edges are kept stretched tightly.

In a further modification of the wrapping apparatus accord ing to the present invention, there are provided a pair of rollers along side of and at the exit end of the exit side pair of conveyors and another pair of rollers to the rear of the former pair of rollers and alongside the exit side pair of conveyors. Thus the former pair of rollers fold rearwardly the forward end portion of the thermoplastic resin film when the article is moved forwardly by the exit side pair of conveyors, while the latter pair of rollers fold the rear end portion of the film forwardly when they are moved toward the side surfaces of the article. The apparatus is also provided with a pair of guide rails at each side of the exit side pair of conveyors adjacent their exit so that they fold the film edges projecting transversely beyond the article up and down when the article is moved forwardly therebeyond.

An embodiment of the driving mechanisms especially useful in the present apparatus for cooperatively adjusting respective distances between said entrance side and exit side pairs of conveyors is provided with dogs on one of said entrance side pair of conveyors which move along with said conveyor, and one of said exit side pair of conveyors is proved with limit switches at positions corresponding to those of said dogs so that they can be actuated by respective said dogs when the conveyor of said entrance side pair of conveyors, so that said dogs and said limit switches cooperate to detect the movement of said conveyor of said entrance side pair of conveyors and cause the movement of said conveyor of said exit side pair in the same direction as said conveyor of the: entrance side pair.

According to the present invention, since the article to be wrapped is wrapped in a compressed state, the article is wrapped tightly without being loosened, and further, since the article is wrapped while it is moved along a straight line, the wrapping operation is made simple and the wrapping time is considerably reduced.

In addition, in the embodiment of the wrapping apparatus according to the present invention which. is provided with inserting levers, the thermoplastic resin film edges projecting transversely beyond the article are folded neatly on both side surfaces of the article with the result that. the wrapped article is given good appearance, and even if the article to be wrapped is relatively large in size, it is nicely wrapped by relatively thin thermoplastic resin film.

Further, the embodiment of the wrapping apparatus provided with pairs of rollers and a pair of guide rails on each side of the exit side of conveyors also results in a neatly wrapped article having a fine appearance.

If the wrapping apparatus according to the present invention is equipped with the aforedescribed driving mechanisms for adjusting the respective distances between the entrance side and the exit side pairs of conveyors, wherein the distance between the exit side pair of conveyors is adjusted automatically in parallel with the variation in distance between the entrance side pair of conveyors, the article to be wrapped is kept in a constant compressed state when it is transferred from the entrance side pair of conveyors to the exit side pair of conveyors.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects of the present invention will become more apparent to those skilled in the art when considered in reference to the following detailed description of the invention in the light of the accompanying drawings in which like reference numerals indicate like parts throughout the several views thereof, and wherein:

FIGS. 1A through 1E illustrate diagrammatically and in perspective the principle of the method for wrapping an article according to the present invention;

FIG. 2 is a diagrammatical view of an embodiment of the preferred apparatus for carrying out the method according to the present invention;

FIG. 3 is a sectional end view of the apparatus shown in FIG. 2 taken along the line III-III of FIG. 2;

FIG. 3A is a partial sectional view taken along the line IIIA-IIIA of FIG. 3;

FIGS. 4A through 4E illustrate diagrammatically the various steps of the principal wrapping process carried out by a second embodiment of the apparatus according to the present invention;

FIG. 5 is an enlarged perspective view illustrating the main portion of the second embodiment of the apparatus according to the present invention;

FIG. 6 is an enlarged perspective view illustrating the slide member of the apparatus shown in FIG. 5;

FIG. 7 is a vertical sectional view of the portion of the slide member shown in FIG. 6 taken along the line VII-VII of FIG.

FIGS. 8 and 9 are diagrammatical views illustrating the attitudes of the inserting lever at its various locations relative to the cam surface, wherein FIG. 8 shows those locations when the lever moves forwardly and FIG. 9 shows those locations when the lever moves rearwardly.

FIG. 10 is a diagrammatical view illustrating the driving mechanisms for driving various moving parts of the apparatus shown in FIGS. 5 to 9;

FIG. 11 is a perspective view illustrating the main portion of the modification of the apparatus according to the present invention shown in FIGS. 4 to 10;

FIG. 12 is an enlarged perspective view illustrating the slide member portion of FIG. 11; 5

FIG. 13 is a perspective view illustrating the slide member portion in cross section taken along the line XIIIXIII of FIG. 12;

FIG. 14 is an enlarged perspective view diagrammatically illustrating the mechanisms for moving the pin to actuate the aws;

FIG. 15 is an elevational sectional view of the driving box of the apparatus shown in FIG. 11 taken along line XV--XV of FIG. 11;

FIG. 16 is a side elevational sectional view of the driving box shown in FIG. 15 taken along line XVI-XVI of FIG. 15;

FIG. 17 is an enlarged perspective view diagrammatically illustrating the mechanisms for moving the guide rod of the apparatus shown in FIG. 11;

FIGS. 18 to 20 are diagrammatical views illustrating the cooperative action between the slide member and the change plate of the apparatus shown in FIGS. 11 to 17 in these different relative positions;

FIG. 21 is a perspective view illustrating diagrammatically the state of the thermoplastic resin film edges projecting transversely beyond the article before they are folded on each side surface of the article;

FIG. 22 is a plan view illustrating the main portion of another embodiment of the apparatus according to the present invention;

FIG. 23 is a diagrammatical view of the apparatus incorporating the embodiment shown in FIG. 22;

FIGS. 24 and 25 are end views illustrating diagrammatically the succeeding steps of the folding process of the film edges carried out by the apparatus shown in FIGS. 22 and 23;

FIG. 26 is a partial sectional view of the apparatus shown in FIG. 22 taken along the line XXVI-XXVI of FIG. 22;

FIG. 27 is a partial sectional view of the apparatus shown in FIG. 22 taken along the line of XXVIIXXVII ofFIG. 22;

FIG. 28 is an end view illustrating the article after completion of the wrapping;

FIG. 29 is a partial cross-sectional view of the apparatus shown in FIG. 22 taken along the line XXIX-XXIX of FIG. 22;

FIG. 30 is a diagrammatical view illustrating the two pairs of conveyors which cooperate to move so that the respective distances between each pair of conveyors are automatically adjusted;

FIG. 31 is a diagrammatical view illustrating the mechanism according to the present invention for carrying out the automatic cooperating adjustment of the distances between conveyors as shown in FIG. 30;

FIG. 32 is a diagrammatical view illustrating the clutch box of the mechanism shown in FIG. 30;

FIGS. 33 and 34 are diagrammatical views illustrating relative positions of dogs and limit switches used in the mechanism shown in FIG. 30;

FIG. 35 is an electrical circuit cooperating with the mechanism shown in FIG. 30; and

FIGS. 36 to 38 are diagrammatical views illustrating the relative positions of dogs and limit switches in various movement of conveyors.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, there is shown diagrammatically the article A is parallel with the surface of film F (FIG. 1A). As article A continues to advance after its forward end surface comes into contact with film F, film F being in a prestressed state, is pulled out from web rolls (not shown) arranged above and below the path of the article so that it wraps article A tightly from its forward end toward its rear end (FIG. 1B). When the upper and lower surfaces as well as the forward end surface of article A are wrapped with film F article A is stopped in its advancement and film F is folded down from the top and up from the bottom along the rear end surface of article A by any suitable means so that the film portions descending and rising respectively come into contact with each other substantially midway of the rear end surface of article A and are fuse welded together (FIG. 1C). After film F is severed at the welded portion, article A is moved again forwardly, whereby both edges of film F projecting transversely from opposite sides'of article A are folded together on the side surfaces of article A by any suitable means to be joined with each other (FIG. 1D). The appearance of article A thus wrapped by film F is shown in FIG. 1E, wherein it will be noted that article A has ribs R on both of its side surfaces and on its rear surface. Referring now to FIG. 2 wherein an embodiment of the preferred apparatus for carrying out the method according to the present invention is diagrammatically shown as it is applied to a machine for use in wrapping a bundle of newspapers or the like with a sheet of thermoplastic resin film such as polyethylene film, a machine frame 1 has provided at its lower part a conventional type conveyor 2 composed of a plurality of plates 3 linked together by an endless chain 4 which travels between an idler chain wheel 5 and a driving chain wheel 6.

On the upper portion of frame 1 there is provided a yoke 7 which is adapted to be moved up and down relative to frame 1 by a mechanism which will be explained in more detail later. Mounted on yoke 7 in confronting relation to conveyor 2 is a conveyor 8 which is substantially identical with conveyor 2 and composed of a plurality of plates 9 linked together by an endless chain 10 which travels between an idler chain wheel 11 and a driving chain wheel 12. Respective shafts l3, 14 of chain wheels 11, 12 of the upper conveyor 8 are, as shown in FIG. 3, journaled for rotation in brackets l5, 16 which are secured to the underside of yoke 7, which is in turn guided by guide rails 17 and 18 secured to the inner surfaces of frame 1 at its upper portion so that yoke 7 is moved upward and downward along guide rails 17, 18. Mounted on an upper frame 19 of the machine is a fluid motor assembly 20, with a piston rod 21 of the fluid motor assembly 20 secured to yoke 7 so that, upon actuation of fluid motor assembly 20, yoke 7 and upper conveyor 8 are moved upward or downward.

Referring now also to FIGS. 3 and 3A, the shaft 22 of driving chain wheel 6 of lower conveyor 2 is journaled for rotation in brackets 23, 24, which are fixedly secured to the inside surfaces of machine frame 1 a driving chain wheel 25 and a gear wheel 26 are fixedly mounted to shaft 22, and an endless chain 27 is reeved as driving chain wheel, the chain 27 being reeved at its lower part on a chain wheel 28 secured to a drive shaft 29. A motor 30 mounted on an underframe 31 of the machine is connected to shaft 29 through a clutch 32. Fixedly secured on a stub shaft S1 journaled for rotation in bracket 24 are a sprocket wheel 33 and a gear wheel 34 which is in mesh with gear wheel 26 on shaft 22. Onstub shaft S1 there is also rotatably mounted a link L1. Driving shaft 14 of upper conveyor 8 is connected to stub shaft S1 through a linkage comprising link L1 and a link L2, one end of link L2 being rotatably mounted on shaft 14 and other end being rotatably mounted on a common intermediate stub shaft $2, on which is simultaneously rotatably mounted one end of link L1. Fixedly secured to intermediate stub shaft S2 are chain wheels 35, 36 on which are respectively reeved endless chains 37, 38, the chains 37 and 38 being respectively reeved on a chain wheel 33 and a chain wheel 33' that are fixedly secured respectively to shaft 22 and to shaft 14. Accordingly, when motor 30 is energized, drive shaft 29 is rotated through clutch 32, which rotates in turn driving shaft 22 through chain wheels 28, 25 and endless chain 27 so that lower conveyor 2 is moved in the direction shown by the arrow X in FIG. 2.

Simultaneously, the rotation of driving shaft 22 of lower conveyor 2 is transmitted to shaft 14 of upper conveyor 8 through gear wheels 26 and 34, chain wheels 33, and endless chain 37, via intermediate stub shaft S2, through chain 36, 33, and endless chain 38 so that upper conveyor 8 is moved in the direction shown by the arrow X in FIG. 2 at the same velocity as that of lower conveyor 2 by the suitable selection, of the dimensions of chain wheels 33, 35, 36 and 33'. It will be apparent that, even when upper conveyor 8 is moved upward or downward together with yoke 7 along guide rails l7, 18, the rotation of motor 30 is transmitted not only to lower conveyor 2 but also to upper conveyor 8 due to the linkage comprising links L1 and L2 connecting driving shafts 14, 22 of upper and lower conveyors 8, as well as endless chains 37, 38 drivingly connecting shafts l4 and 22.

At the exit side of upper and lower conveyors 2, 8 is stretched or spread orthogonally to the direction of movement of the conveyors a sheet of thermoplastic resin film F. The film is a polyethylene film for example, having the characteristics of being easily welded by heat and easily cut by a cutter. In this case, the upper and lower ends of film F are respectively led through each set of guide rollers and dancer roller 39, 40, 41 and 42, 43, 44 to respective rolls 45, 46 so that each end of film F is wound on each roller 45, 46 as respective webs 47, 48.

At the initial state, upper conveyor 8 is held in its uppermost position by fluid motor assembly 241 as shown by the full line in FIG. 2. After starting motor 30, an article A to be wrapped such as a bundle of newspapers is put on plates 3 of lower conveyor 2, and when it is moved to a midportion of conveyor 2 its position is detected by any suitable means such as photoelectric means of any known type (not shown) so that clutch 32 is disengaged to stop the movement of conveyor 2. Simultaneously with the stoppage of conveyor 2, upper conveyor 8 is lowered by the actuation of fluid motor assembly 20 so that article A is compressed between plates 9 and 3 of upper and lower conveyors 8 and 2 as shown by heavy dotdash-lines in FIG. 2. When article A is compressed in a desired amount, upper and lower conveyors 8 and 2 are moved forward again by the engagement of clutch 32 to feed article A toward the exit of upper and lower conveyors 8 and 2. As soon as the forward end H of article A comes into contact with thermoplastic film F spread tightly at the exit of conveyors 8 and 2, it pushes film F so that film F is paid out or fed from rolls 45 and 46, with film F kept tightened by the action of dancer rollers 41 and 44.

At the exit side of conveyors 2 and 81 there is arranged a pair of lower and upper conveyors 49 and 50 which have constructions substantially identical with conveyors 2 and 8 to feed article A in the same direction as that of conveyors 2 and 8, with a space between the adjacent ends of the two pairs of conveyors 2, 8 and 49, 50.

Conveyors 49 and 59 are adapted to be moved in up and down directions in association with the movement of conveyors 2 and 8 in those directions, so that, when conveyor 8 is lowered to stop at a definite position above conveyor 2, conveyor 50 is also lowered to stop at the same level as that of conveyor 8. Accordingly, article A fed from conveyors 2 and 8 with film F being wrapped around it is smoothly transferred between conveyors 49 and 50 with the compressed state being maintained. When article A is fed onto conveyor 49 centrally as shown by heavy dot-dash-lines in FIG. 2, its position is detected by any suitable means such as photoelectric means (not shown) to stop the advancement of conveyors 49and 50.

Between the pairs of conveyors 2, 8 and 49, 50 there are arranged respective seal means at upper and lower positions each comprising a set of rolls 51, 52, 53, 54 and a heat seal device 55, 56 as shown by full lines in FIG. 2. These seal devices 55, 56 are well known in the art and so will not be described further. At the position of article A on conveyor 49 as shown by dot-dash-liries in FIG. 2, seal means 51, 52, 55, and 53, 54, 56 approach each other by any suitable means (not shown) so that they are effective to lap thermoplastic resin films F together at the rear side of article A as shown by dot-dash-lines in FIG. 2, and then electric current is fed to each heat seal device 55 and 56 to fuse weld films F at their lapped portion, and thereafter films F are severed by a suitable cutter knife (not shown) at the welded portion. In this case, it

will be appreciated that since film F is joined together at the fuse welded portion with a substantial area, after film F having been severed along the centerline of the welded region, article A is wholly wrapped at its rear end by fuse welded film, and at the same time film F is fuse welded together at the severed end portion, so that it is kept tightened as before between guide rollers 39 and 42 by the action of dancer rollers 41 and 44. After completion of the fuse welding of film F at the rear side of article A, article A is moved again forwardly by conveyors 49 and 50. At each side of these conveyors 49 and 50 there are arranged guide plates 57, 58. Guide plates 57 and 58 are disposed in confronting relation with each other and converge toward the direction of the movement of conveyors 49, 50 so that the distances between the inner surfaces of guide plates 57 and 58 become smaller toward the exit of conveyors 49, 50. Both edges of the film F projecting transversely beyond the sides of article A as viewed in the moving direction of article A are respectively folded along the side surfaces of article A by guide plates 57, 58 as article A moves forward alongside guide plates 57, 58 with the movement of conveyors 49, 50, and finally the upper and lower portions of the edges of film F projecting transversely from article A are joined together at the exit of guide plates 57, 58. At the exit of guide plates 57, 58 there are arranged a pair of heat seal means in alignment with guide plates 57, 58. The heat seal means respectively comprised of a pair of conveyor type belts S9, 60 travelling in the direction shown by the arrows Y, Y in FIG. 2, each of which is heated from inside by any suitable well-known heating means 61, 62, which will not be described further. After leaving guide plates 57, 58 and on entering the heat seal device, each lapped film portion on each side of article A is fuse welded together with the progress of article A which is carried on a delivery conveyor 63 disposed at the exit side of conveyors 49, 50 and moving in the direction shown by the arrow Z in FIG. 2.

The feature of the apparatus shown in FIGS. 2 and 3 is in that the wrapped thermoplastic resin film F has ribs R at both side surfaces and rear side surfaces formed by the fuse welded portions of film F as shown in FIG. 1E, which results in giving a poor appearance. Further, in the course of the wrapping procedure, before lapping the film edges projecting transversely beyond both sides of article A, the projecting edges must be kept in elongated condition as shown in FIG. 1B so that they are properly led between guide plates 57, 58 as article A moves forwardly between conveyors 49, 50. Accordingly, the film to be used for this process is required to be relatively thick so as to be stifi and the dimension of the article to be wrapped is limited to relatively small ones.

In FIGS. 4 to 10 there is shown a second embodiment of the apparatus according to the present invention. This apparatus can wrap an article having relatively larger dimensions with relatively thin film contrary to the apparatus of the first embodiment shown in FIGS. 2 and 3.

Now referring to FIG. 4, wherein the steps of the wrapping process carried out by the apparatus embodying the present invention in the second form are shown, an article A to be wrapped is fed in the direction shown by the arrow X in front of a sheet of thermoplastic resin film F spread in the path of movement of article A on the first pair of conveyors (not shown) as in the first embodiment. When article A is wrapped by film F' as shown in FIG. 48 about one third portion of its length measured in the direction of its movement from its forward end, levers L arranged on each side of article A are introduced into the space formed between film F and article A as shown by the arrow Y,.

Levers L move forwardly as shown by the arrow Y at slightly higher speed than that of article A so that they pull the forward end of film F as shown in FIG. 4C. When article A reaches a position where the seal process at its rear side takes place, it stops and levers L begin to retract out of the spaces as shown by the arrow Y in FIG. 4D and simultaneously a pair of endless belts B disposed on each side of article A lying one upon another approach each other as shown by the arrow Z in FIG. 4D so that the film edges projecting transversely beyond the sides of article A are held between belts B. After completion of the fuse welding of film F at the rear side of article A the article is moved forwardly as shown by the arrow X in FIG. 4E so that the projecting edges of film F are joined together with the pair of belts B moving in the direction as shown by the arrow x in FIG. 4E.

FIGS. 5 to show the apparatus carrying out the process explained above and shown in FIG. 4A-E.

Now referring mainly to FIGS. 5 and 6, a rail 100 is mounted on a machine frame 101 at each side of conveyor 49. Slidably mounted on rail 100 is a slide member 102 which is moved along rail 100 by a rope or a chain 103 each end of which is secured to slide member 102 through any suitable means such as brackets 104, 105 projected from the upper surface of slide member 102 and rings 106, 107 secured at each end of rope 103.

Rope 103 reeves over rope pulleys 108, 109 each secured to shafts 110, 111 respectively which are journaled for rotation in bearingboxes 112, 113 respectively mounted on each end of machine frame 101. One end of shaft 110 protrude through bearing box 112 outwardly from machine frame 101 and at its outer end a sprocket wheel 114 is secured so that shaft 110 is adapted to be rotated through an endless chain 115 reeved on sprocket wheel 114 and a sprocket wheel 116 which is made to be rotated through a prime mover as will be explained later. Accordingly, slide member 102 is moved along guide rail 100 forwardly or rearwardly by the movement of rope 103 when the prime mover is rotated clockwise or counterclockwise. Rotatably fitted in slide member 102 at its inward side is a pivot 117 to which is fixedly attached at the upper end thereof above the slide member 102 a lever 118. A guide lever 119 is fixedly attached to the pivot 117 beneath slide member 102 and an inserting lever 120 is pivotally attached to the pivot 117 at the end thereof. Inserting lever 120 is held in position on pivot 117 by a nut 121 threaded to the end of pivot 117 as shown in FIG. 7. A tension coil spring 124 is mounted between a pin 122 secured to lever 118 at its outer end and a pin 123 secured to slide member 102 at its outward side so that a roller 125 rotatably mounted on guide lever 119 at its outer end by a pivot 126 is urged to be pressed against a cam surface 127 which is formed lengthwise on the inside surface of guide rail and has obliquely cut end surfaces 128, 129. Disposed around pivot 117 between guide lever 119 and inserting lever is a torsion coil spring with its each end being fixedly secured to the guide lever and inserting lever respectively so that a projection or a stopper 131 fixedly secured to inserting lever 120 at its base portion is urged to be pressed against the side surface of guide lever 119. As best shown in FIG. 6, guide lever 1 19 and inserting lever 120 are arranged so as to assume an L shape as viewed from above when roller 125 of guide lever 119 rests on the straight line portion of cam surface 127.

Inserting lever 120 operates as follows:

Initially, slide member 102 is located at the left end of guide rail 100 as viewed in FIG. 5 and at this state guide lever 119 is at the outside of cam surface 127 and a limit switch L8] is in contact with roller 125 as shown in FIG. 8 at A. When slide member 102 moves to the right as viewed in FIG. 5 by the movement of rope 103 guide lever 119 is rotated clockwise by the engagement of its roller 125 with cam surface 128 against the force of tension coil spring 124 in FIG. 8 at B so that inserting lever 120 is also rotated clockwise about pivot 117 by the engagement of its projection 131 with the side surface of guide lever 119 against the force of torsion coil spring 130, whereby inserting lever 120 is disposed at about a right angle with the straight line portion of cam surface 127. At the end of the travel of slide member 102, as indicated at C in FIG. 8, inserting lever 119 assumes a position D as shown in FIG. 8 wherein guide lever 119 rotates counterclockwise by the action of tension coil spring 124 so that inserting lever 120 simultaneously rotates counterclockwise by the action of torsion coil spring 130, whereby inserting lever 120 assumes a position substantially parallel with the straight line portion of cam surface 127. At the same time, roller 125 comes into con tact with a limit switch LS2.

When slide member 102 returns to its initial position due to the reverse movement of rope 103, guide lever 119 rotates in a counterclockwise direction since roller 125 engages with the straight line portion of cam surface 127 via the obliquely cut end surface 129 as shown in FIG. 9 at E so that inserting lever 120 is released from the engagement of its projection 131 with the side surface of guide lever 119 as shown in FIG. 9 at E, and the tip ofinserting lever 120 comes into contact with cam surface 127. Upon disengagement of roller 125 from cam surface 127, as in position F shown in FIG. 9, guide lever 119 rotates clockwise to rotate inserting lever 120 clockwise with the engagement of projection 131 with the side surface of guide lever 119 as shown in FIG. 9 at G.

An example of mechanisms for driving the moving parts of the present apparatus is shown schematically in FIG. 10. The rotation of the motor 131 is transmitted to a shaft 132 connected to the motor shaft and a gear 133 secured to shaft 132 transmits the rotation of motor 131 to a shaft 134 connected to a reduction gear 135 through a gear 136 secured to shaft 134 and an intermediate gear 137 meshing with both gears 133, 136. Fixedly connected to the reduction gear shaft 134 a cam shaft 138 which carries a number of cams 139. These cams 139 respectively function to move upward or downward the pairs of belts B previously described, to open or close the fuse welding device for the film extending beyond the rear side of the article, to start or stop the article-feeding conveyors, or to actuate the limit switches LS1, LS2 to issue signals for starting, reversing or stopping inserting levers 120. The rotation of motor 131 is also transmitted to an electric clutch 140 via shaft 132. Fixedly mounted on an output shaft 141 of electric clutch 140 are sprocket wheels 142, 143, 144.

Sprocket wheels 142 and 143 transmit the rotation of output shaft 141 respectively to the article feed conveyors 2 and 49 through sprocket wheels 145, 146 each secured to respective conveyor shafts and endless chains 147, 148 each reeved around sprocket wheels 142, and 143, 146. (This constitutes an alternative transmission mechanism for conveyor 2 shown in FIGS. 2, 3 and 3A Sprocket 1445 has an endless chain 169 reeved on it which is also reeved on a sprocket wheel 150 that is mounted on an input shaft 151 of an inserting lever driving device 152. The rotation of input shaft 151 is transmitted, on the one hand, to a first output shaft 153, via an electric clutch 154, and, on the other hand, to an intermediate shaft 155 through gears 156, 157 each secured to input shaft 151 and intermediate shaft 155 as well as an intermediate gear 150 meshing with both gears 156, 157. The rotation of intermediate shaft 155 is transmitted to a second output shaft 159 through an electric clutch 160, and thence to first output shaft 153 through gears 161 and 162, respectively secured to first and second output shafts 153, 159. It will be understood that the driving device 152 for inserting lever 120 constitutes a well-known reverse gear which serves to transmit the rotation of input shaft 151 to first output shaft 153 either in the identical direction or in the reverse direction owing to the selective energization of electric clutch 1541 or 160, and since the device is widely known in the art, a detailed description of its construction and operation is omitted. At the outer end of first output shaft 153 is secured a sprocket wheel 116 which is adapted to rotate sprocket wheel 114 secured to shaft 110, as stated above, through endless chain 115 reeved on them. The operation of the apparatus shown in FIGS. 5 to will next be explained:

Upon movement of the article from the position as shown in FIG. 4A to that shown in 18 the limit switch LS1 is actuated to energize electric clutch 1541 so that slide member 102 is moved to rotate inserting lever 120 for projecting it into the space between the film edges. Midway of the change from the state as shown in FIG. 4C to that in FIG. 6D, a limit switch (not shown) is actuated to disengage clutch 140 so that con veyors 2, 49 and slide member 102 with inserting lever 120 stop their movement. Upon completion of the fuse welding of the thermoplastic resin film at the rear side of the article by the fuse welding device under the control of the cam devices 139 as aforesaid, clutch 1 10 is again engaged to move the article further, and, at the same time, slide member 102 begins to move again. When inserting lever 120 reaches the position D in FIG. 0, inserting lever 120 immediately retracts from the position between the film edges and actuates the limit switch LS2 to disengage clutch 154 and engage clutch 160, which results in slide member 102 beginning to move rearward to return to its initial position. When slide member 102 reaches its original position limit switch LS1 is actuated to disengage clutch 160 so that slide member 102 stops its movement.

According to the second embodiment of the present invention, since the inserting lever is introduced between the thermoplastic film edges adjacent the forward end of the article before the completion of the wrapping process, its therebetween is ensured, and further, since it travels at a slightly greater velocity than that of the article, the projecting ends or edges of the film are kept neatly stretched.

In the embodiment described above and shown in FIGS. 41 to 10, the operation of the slide member is controlled by electrical means such as limit switches. However, such a control also can be accomplished mechanically as will be described and shown in FIGS. 11 to as modification ofthe second em bodiment of the apparatus according to the present invention.

Now referring to FIG. 11 which shows a general view of this modified apparatus, each slide member 200 has an inserting lever 201 pivotally mounted thereto and is slidably supported on guide rods 202, 203 which are arranged above respective machine side frame 204 in vertically aligned relation between a bracket 205 and a driving box 206 mounted on machine frame 204 An endless rope 207 is adapted to be moved in association with the driving parts of the article feed conveyors and is spanned between bracket 205 and driving box 206 in such a manner that it passes through sliding member 200 at its upper and lower portions.

FIGS. 12 and 13 show the slide member portions on an enlarged scale.

The upper and lower portions of sliding member 200 are provided with claws or clamps 200, 209 respectively and the upper and lower portions, respectively, of the sliding member 200 are formed with chucks 210, 211 in cooperative association with claws 2013, 209. Claws 2011, 209 are fixedly secured to the upper and lower ends, respectively of a pin 212 fitted in a bore 213 formed in the body of sliding member 200 as shown in FIG. 13. The pin 212 is freely shiftable upward and downward through the bore 213 for adjusting the positions of the claws with respect to the chucks.

Thus, when pin 212 is moved upward, rope 207 is grasped between claw 209 and chuck 211, and when the pin 212 is moved downward, the rope 207 is grasped between claw 200 and chuck 210. It will be evident that when one set of claw and chuck is actuated to grasp the rope, the other set is actuated to release the rope. As shown in FIG. 13 pin 212 has secured thereto at its midportion a piece 214 having a groove 215 which piece is located within an opening 216 formed in the body of slide member 200. Groove 215 receives an end of a pin 217 which is secured to one end of an arm ofa crank lever 215 pivotally mounted to slide member 200 by a pivot 219 as shown in FIG. 141. On one end of the other arm of the crank lever 218 is fixedly connected a pin 220. A rod 221 is pivotally connected to pin 220 at its one end and is supported through a hole 222 of a bracket 223 fixedly secured to sliding member 200 at its lower portion. A coil spring 2241 is disposed around rod 221 between pin 220 and bracket 223 such that spring 224 acts to rotate crank lever 218 counterclockwise about pivot 219 to keep crank lever 218 at its neutral position. When pin 220 is shifted from its neutral position as shown at b in FIG. 14 to the position a, pin 217 is pushed upward by crank lever 218 so that claw 209 is thrust against rope 207 to grasp it against chuck 211. On the contrary, when pin 220 is moved downward to the position 0 as shown in FIG. 14, pin 217 is pushed downward by crank lever 218 so that claw 208 is thrust against rope 207 to grasp it against chuck 210.

As shown in FIG. 12, a bracket 225 having a slot 226 is secured to the rear outer surface of sliding member 200. A generally channel-shaped change plate 227 is slidably supported in slot 226 and a groove 220 formed at each end of change plate 227 engages with the guide rod 203. An arcuate slot 229 in the web portion of change plate 227 receives pin 220 therethrough so that, when change plate 227 is moved to the right or left in a manner to be explained in detail later, pin 220 is also moved to the right or left to operate claw 200 or 209 to grasp the upper portion or lower portion of rope 207 associated with chuck 210 or chuck 211 respectively.

FIGS. 15 and 16 show the arrangement of guide rods 202 and 203 inside of driving box 206. Guide rod 202 is fixedly secured to bracket 205 and driving box 206 at its opposite ends respectively, and stops 230 and 231 fixedly mounted thereon its ends. Guide rod 203 is slidably mounted on bracket 205 and driving box 206 so that it can be freely moved to the right or left as viewed in FIGS. 11 and 15. Further, stops 232 and 232 are fixedly mounted on movable guide rod 203 near its ends.

The driving mechanism for moving movable guide rod 203 to the right and left are shown in FIGS. 1.1, 15, 16 and 17. As shown in FIG. 17, a pin 234 fixed to one end ofa lever 235 engages in a groove 233 formed on a portion of movable guide bar 203. The lever 325 is fixedly secured to a shaft 236 at its other end. Shaft 236 is journaled for rotation in driving box 206 and a lever 237 is secured at one end thereof to the end of shaft 236 projecting outwardly through driving box 206. A connecting rod 230 is pivotally connected at the other end of lever 237. As shown in FIG. 11, the tip portion of a lever 239 is projected through the gap between the conveyor and the side frame so that it is adapted to be pushed down by the advancing article and is secured one end to a shaft 240 which is pivotally supported in the side frames. Lever 239 is pulled by a tension coil spring 2 11 so that it is held in an inclined position. A lever 2412 is secured at one end thereof to shaft 260 and is pivotally connected to connecting rod 238 at its other end.

In view of the foregoing d esgription it will be apparent that when the tip of lever 239 if pushed down by the article moving with the conveyor, it rotates counterclockwise, which causes the counterclockwise rotation of shaft 236 through shaft 240, lever 242, connecting rod 238 and lever 237, so that movable guide rod 203 is moved to the left as viewed in FIG. 17 through the engagement of pin 234 secured to lever 235 and groove 233 formed on rod 203.

As soon as the article has moved past the tip of lever 239, lever 239 returns to its original position under the action of tension coil spring 241 so that movable guide rod 203 is moved to the right as viewed in FIG. 17.

Rope 207 is reeved on a rope pulley 247 secured to a shaft 248 rotatably journaled in driving box 206. One end of shaft 248 projects beyond driving box 206 and has secured thereto a sprocket wheel 249 which is adapted to be rotated by a driving mechanism (not shown) through an endless chain 250 (see FIG. 16). The operation of the slide member 200 with the movement of the various moving parts as stated above is diagrammatically shown in FIGS. 18 to 20. As shown in FIG. 18, when slide member 200 is initially set so that its right side face is in contact with stop 230 mounted on guide rod 202, the right side face of change plate 227 is in contact with stop 231 mounted on movable guide rod 203 so that change plate 227 is in neutral position. Accordingly, pin 212 is also in the neutral position, that is, pin 220 locates at the position b as shown in FIG. 14 so that neither of the clamps 208 and 209 cooperate with chucks 210 or 211 to grasp rope 207. The position stated above is that of the beginning of the operation. When the free end of lever 239 is pushed down by the advancing article so that movable guide rod 203 is moved to the left as viewed in FIG. 17 through shaft 240, lever 242, connecting rod 238, lever 237 and lever 235, stop 231 pushes change plate 227 to the left to push down pin 212 as shown in FIG. 19 so that clamp 208 cooperates with chuck 210 to grasp the upper part of rope 207, resulting in that slide member 200 is moved to the left by moving rope 207 as viewed in FIG. 11.

When slide member 200 is moved to the left as viewed in FIG. 11 to the end of its stroke abutting against stop 231 as shown in FIG. 20, the left side surface of change plate 227 simultaneously comes into contact with stop 232, so that pin 212 is thrust up to its neutral position, resulting in that clamp 208 release the upper portion of rope 207 to stop sliding member 200.

Along with further movement of the article, guide rod 203 is moved to the right as viewed in FIG. 11 to return to its initial position as aforesaid. Accordingly, stop 232 fixedly mounted on moving guide rod 203 at its left end pushes the left side surface of change plate 227 to raise pin 212 so that clamp 209 cooperates with chuck 211 to grasp the lower portion of rope 207. Consequently, sliding member 200 is moved to the right as viewed in FIG. 11 by the lower portion of rope 207 until it abuts against stopper 230 and stops at the initial position.

Thus, as opposed to the second embodiment, the operation of the third embodiment of the present invention is more reliable, since the actuating signal is initiated by the thrusting down motion of the lever due to the moving article, rather than the electrical means utilized in the second embodiment to effect the motion ofthe inserting levers.

In the various embodiments of the present invention thus far described, both edges of the thermoplastic resin film project transversely beyond the sides of the article where they are fuse welded together to complete the wrapping, and these welded portions protruding outwardly from both side surfaces of the article give the wrapped article a poor appearance (see FIG. 1E).

In order to improve the appearance of the wrapped article, the present invention provides a further embodiment of the apparatus carrying out the present invention.

FIGS. 21 to 29 show this fourth embodiment of the present invention. As in the previous embodiments, it is assumed that the thermoplastic resin films at the rear end surface of the article has been fuse welded, both that both thermoplastic resin 12 film edges project transversely beyond the sides of the article such as shown in FIG. 21.

To fold the film edges a, b, c and d as shown in FIG. 21 two brackets 300, 301 are provided on the machine frame at each side of the conveyor as shown in FIG. 22, and an axle 302 is mounted on each bracket 300, 301, each of which rotatably carries a roller 303 so that each roller 303 projects inwardly to contact with each side surface of article A at its midportion measured in the direction of its height when it is moved by conveyor 49.

Accordingly, when article A moves from the position shown at B in FIG. 23, each roller 303 pushes the forward end portion b of film F which protrudes laterally from the forward end of article A (see FIG. 21) and folds it so that it comes into contact with each side surface of the article as shown in FIG. 24.

Shortly after the folding action of roller 303 an arm 304 pivotally connected to each of brackets 300, 301 by a pivot 305 is rotated inwardly as shown by the arrow R in FIG. 22 so that a roller 306 which is rotatably mounted on arm 304 by a pivot 307 folds the rear portion c of the film forwardly on the side surface of article A as shown in FIG. 25. The pivotal movement of arm 304 can be effected by any suitable means, an example thereof being shown in FIG. 26, wherein a gear 308 fixedly secured to pivot 305 meshes with a gear 309 which is secured to a shaft 310, which is in turn adapted to be rotated intermittently by any one of the driving mechanisms of the machine, such as the prime mover of the conveyors, through a cam or the like.

After the projected edge portions b and c of the thermoplastic resin film are folded on the side surfaces of article A rearwardly and forwardly respectively, the remaining upper and lower projecting portions a and d of the film (FIG. 21) are folded downward and upward, respectively, on the side surfaces of article A by a pair of arcuately shaped guide rails 311, 312 disposed on each side of article A adjacent thereto when article A moves forwardly. The guide rails 311, 312 are arranged so that the vertical distance between them is gradually decreased in the direction of the movement of conveyor 49 as shown in FIG. 27. Accordingly, when article A has passed between the pairs of guide rails 311, 312 the upper and lower projecting edge portions 0 and d of the film are folded together on the side surfaces of article A as shown in FIG. 28. The folded portions are welded together or joined by any suitable manner such as by interposing adhesives between the folded film portions to be joined.

In the present invention, two sets of conveyors connected in series are provided, the first conveyor of the set is for feeding an article to be wrapped as it is compressed, and the second conveyor of the set is for feeding the article in the compressed state. Therefore, it is necessary that the latter set of conveyors be adjustable so that the distance between the upper and lower conveyors of the second set is exactly the same as the distance between the upper and lower conveyors of the set. The present invention also provides means by which such distance adjustment may be automatically carried out.

FIGS. 30 to 38 show an example of such means. Now referring to FIG. 30, the first set of conveyors I and the second set of conveyors II comprise, respectively, upper and lower conveyors 400, 401 and 402, 403, whereby when an article to be wrapped is fed to the first set I between upper and lower cor:- veyors 400, 401, it is compressed between the conveyors when they are moved toward each other. In this case, the distance between the conveyors 400, 401 varies depending on the height of the article. When conveyors 400, 401 are moved to feed the compressed article toward the second set of conveyors II, the distance between conveyors 402 and 403 must be adjusted so as to be substantially equal to that between conveyors 400 and 401. At the same time, when the distance between the first set of conveyors 400, 401 is at its maximum value, that of the second conveyors 402, 403 must also be at its maximum value.

FIG. 31 shows the driving mechanisms for moving both sets of conveyors, wherein the mechanisms for the first set of conveyors is identical to those for the second set of conveyors.

Conveyors 400, 401 (or 402, 403) are mounted on supporting frames 404, 405 (or 404,, 405,) respectively through a shaft 406 and a pair of bearings 407, 400. Supporting frames 404, 405 are arranged so that they simultaneously move downward and upward, respectively through a screw-threaded shaft 409 and nuts 410, 411 engaging therewith, the nuts 410, 411 respectively attached to supporting frames 404, 405. In this case, it is assumed that nut 410 and the portion of shaft 409 engaging therewith are formed by a left-handed screw, while nut 411 and the portion of shaft 409 engaging therewith are formed by a right-handed screw. Thus, both nuts 410, 411 move toward or away from each other depending on the direction of rotation of shaft 409.

Shaft 409 is connected to a clutch box 412 through a bevel gear 413 secured at the upper end of shaft 409 and a bevel gear 414 meshing therewith. Clutch box 412 is drivably connected to a motor 415 through any suitable means such as sprockets 416, 417 and an endless chain 410.

Clutch box 412 comprises, for instance, as shown in FIG. 32, two clutches CL1 and CL2, two gear trains 419, 420, and according to the engagement of either of clutch CL1 or CL2 an output shaft 421, that is, the shaft which has bevel gear 414 is made to be rotated either in clockwise or counterclockwise direction. For example, when clutch CL1 is engaged, shaft 409 rotates in the clockwise direction so that conveyors 400, 401 are moved away from each other, while when clutch CL2 is engaged, shaft 409 rotates in the counterclockwise direction so that conveyors 400, 401 are moved to approach each other.

As shown in FIG. 30, a pair of dogs 422 and 423 are provided on supporting frame 404 of conveyor 400 of the first set of conveyors I, while a pair of limit switches LS1 and LS2 are provided on supporting frame 404' of conveyor 402 of the second set of conveyors II at the positions corresponding to dogs 422 and 423, respectively, so that limit switches LS1 and LS2 are adapted to come into contact with dogs 422 and 423 respectively. Dogs 422 and 423 respectively have shapes as shown in FIGS. 33 and 34, that is, dog 422 has a short length, while dog 423 has a long length, and each corresponds to limit switches LS1 and LS2 respectively.

The electrical circuit for controlling the actuation of clutches CL1 and CL2 is shown in FIG. 35 and in this case, it is supposed that clutches CL1 and CL2 are for the first set of conveyors I. In FIG. 35, switch LS1 and a magnetic switch A1, and switch LS2 and a magnetic switch A2 are respectively connected in series, whereby upon closing switch LS1 or LS2, magnetic switch A1 or A2 is closed respectively. The contact A2S of magnetic switch A2 is closed to feed electric current when magnetic switch A2 is energized, and the contacts A and A of magnetic switches A1 and A2 respectively are opened to shut electric current when respective switches A1 and A2 are energized, and closed when they are deenergized.

When limit switches LS1 and LS2 come into contact with dogs 422 and 423 respectively so that those limit switches are actuated, as shown in FIG. 36, both clutches CL1 and CL2 are disengaged, that is, screw-threaded shaft 409 is at a standstill.

When conveyor 400 of the first set I moves downward through supporting frame 404 so that both dogs 422 and 423 also move downward, limit switches LS1 and LS2 are disengaged from dogs 422 and 423 as shown in FIG. 37 so that limit switches LS1 and LS2 are turned off. Accordingly, magnetic switches A1 and A2 are not energized, so, as stated above, their contacts A10 and A20 are closed to engage clutch CL2. Upon engagement of clutch CL2, screw threaded shaft 409 (of the second set of conveyors II) is rotated reversely so that conveyors 402 and 403 of the second set II move to approach each other. That is, in FIG. 37, both switches LS1 and LS2 move downward and when switch LS1 comes into contact with dog 422 the movement of conveyor 402 stops.

On the other hand, as shown in FIG. 30, when conveyors 400 and 401 of the first set I move so that the distance between them becomes great, both dogs 422 and 423 move upward so that switch LS1 disengages from dog 422, while switch LS2 remains in contact with dog 423. Accordingly, only magnetic switch A1 is deenergized so that clutch CL1 is engaged, and as stated above, screw threaded shaft 409 (of the second set of conveyors II) is rotated in a forward direction, and conveyors 402 and 403 are moved so as to increase the distance between them, which results in moving limit switches LS1 and LS2 downward.

Thus, according to such an arrangement of the dogs and the limit switches, the movements of the two sets of conveyors to increase or decrease the distances between the conveyors of each set of conveyors are controlled automatically by means of the movement of one set of conveyors to enlarge or decrease the distance between the conveyors of that set, whereby the movement of the other set of conveyors to enlarge or decrease the distance between them follows the movement of the first set of conveyors.

Accordingly, prior to transferring the compressed article from the first set of conveyors to the second set of conveyors, the distance between the latter conveyors is automatically adjusted so as to be same as that between the former conveyors, which makes it possible to eliminate the manual adjustment of the distance between the second set of conveyors depending on the height of the article to be wrapped.

It is to be understood that although certain forms of this invention'have been illustrated and described, his not to be limited thereto except insofar as such limitations are included in the following claims: 4

We claim:

1. A method for wrapping an article, comprising the steps of compressing the article, advancing said article in a compressed state toward a sheet of thermoplastic resin film which is tightly spread in front of said article transverse to the direction of movement of said article, wrapping said article with said film from its forward end toward its rear end in connection with its movement as said article continues advancing, folding said film on the rear end surface of said article, fuse welding together the folded portions of said film at the rear end surface of said article, severing said film at the fusewelded portion, moving the edge portions of said film rojecting transversely beyond the sides of said article forward at a faster rate than said article as said article is further moved forwardly to stretch said edges, folding said stretched edges together, and fuse welding the stretched edges together.

2. A machine for wrapping an article comprising a pair of spaced-apart feed conveyor means for advancing an article to be wrapped while it is subjected to compression between the spaced pair of feed conveyor means, means for feeding webs of thermoplastic resin film so that a sheet of said film is disposed perpendicular to the movement of said article and is caused to be'fed from said web feed means when the forward end surface ofsaid moving article comes into contact with said film, fuse-welding means arranged forwardly of said feed conveyor means for fuse welding said film, severing means arranged forwardly of said feed conveyor means for severing said fuse welded film, a pair of spaced-apart transferring conveyor means arranged forwardly of said fuse welding and severing means to advance said article in a compressed state, means operatively associated with said pair of feed conveyor means and with said pair of transferring conveyor means to automatically adjust the space between the pair of transferring conveyor means in response to changes in the space between the feed conveyor means, and folding means arranged alongside said transferring conveyor means for folding the edges of said film projecting transversely beyond said article on said side surface thereof as the article is further advanced.

3. A machine for wrapping an article comprising feed means for advancing an article to be wrapped while it is subjected to compression, means for feeding webs of thermoplastic resin film so that a sheet of said film is disposed perpendicular to the movement of said article and is caused to be fed from said means when the forward end surface of said moving article comes into contact with said film, fuse-welding means arranged forwardly of said feed means for fuse welding said film, severing means arranged forwardly of said feed means for severing said fuse-welded film, transferring means arranged forwardly of said fuse welding and severing means to advance said article in a compressed state, folding means arranged alongside said transferring means for folding the edges of said film projecting transversely beyond said article on each side surface thereof as the article is further advanced, said feed means comprising an entrance side pair of conveyors disposed one above the other, means for adjusting the distance between said entrance pair of conveyors, said transferring means comprising an exit side pair of conveyors disposed one above the other, means for adjusting the distance between said exit side pair of conveyors in cooperation with the adjustment of the distance between said entrance side pair of conveyors, an inserting lever on each side of said exit side pair of conveyors, means connected to each said inserting lever for introducing said inserting lever into a space defined by the forward end portion of said thermoplastic resin film, the side surface of said article and the edges of said film projecting transversely beyond said article as said film is caused to be fed from said means upon the advancement of said article, and means for moving said inserting lever at a slightly higher velocity than that of said article.

4. A machine for wrapping an article as set forth in claim 2, wherein said adjusting means comprises driving mechanisms for cooperatively adjusting respective distances between said entrance side pair of conveyors and said exit side pair of conveyors, said driving mechanisms including dogs mounted on one of said entrance side pair of conveyors for movement therewith and limit switches on one of said exit side pair of conveyors at positions corresponding to the positions of said dogs so that the switches are actuated by respective said dogs when said conveyor provided with said dogs moves up or down, whereby said dogs and said limit switches cooperate to detect the movement of said conveyor having said dogs and to cause the movement of said conveyor having said limit switches in the same direction as that of said conveyor having dogs.

5. A machine for wrapping an article as set forth in claim 3, wherein said inserting lever is pivotally mounted on a slide member which is slidable on a rail disposed parallel to said exit side pair of conveyors, said means connected to said inserting lever for introducing said inserting lever into said space comprising a projection secured to said lever and a guide lever rotatably mounted on said inserting lever axis, said guide lever, engaging and riding on a cam surface provided on said rail as said slide member is moved in association with the movement of said article to cause said inserting lever to be introduced into said space, and means for moving said slide member at a velocity slightly higher than that of said article.

6. A machine for wrapping an article as set forth in claim 3,

wherein said inserting lever is mounted on a sliding member, said sliding member being mounted on a fixed guide rod and a movable guide rod, said guide rods being parallel with each other and supported between a bracket and a driving box, said bracket and said driving box each mounted on a frame alongside said exit side pair of conveyors, pulleys mounted on said bracket under said driving box, an endless rope reeved on said pulleys, said endless rope passing through said sliding member at its upper and lower portions, each of said upper and lower portions provided with a clamp and a chuck mechanism cooperating to grasp a portion of said rope alternately when either one of said clamp and chuck mechanisms is engaged, said clamp and chuck mechanisms being actuated through said movable guide rod when it is engaged by said article as it is moved along by said exit side pair of conveyors.

7. A machine for wrapping an article comprising feed means for advancing an article to be wrapped while it is subjected to compression, means for feeding webs of thermoplastic resin film so that a sheet of said film is disposed perpendicular to the movement of said article and is caused to be fed from said means when the forward end surface of said moving article comes into contact with said film, fuse welding means arranged forwardly of said feed means for fuse welding said film,

severing means arran ed forwardly of said feed means for severing said fuse we ded film, transferring means arranged forwardly of said fuse welding and severing means to advance said article in a compressed state, folding means arranged alongside said transferring means for folding the edges of said film projecting transversely beyond said article on each side surface thereof as the article is further advanced, said feed means comprising an entrance side pair of conveyors disposed one above the other, means for adjusting the distance between said entrance pair of conveyors, said transferring means comprising an exit side pair of conveyors disposed one above the other, means for adjusting the distance between said exit side pair of conveyors in cooperation with the adjustment of the distance between said entrance side pair of conveyors, said folding means comprising a pair of rollers each rotatably disposed at each side of said exit side pair of conveyors adjacent its exit end, a pair of rollers each rotatably mounted on one end of an arm adjacent the entrance end of said exit side pair of conveyors, said arm pivotally mounted at its other end on a frame alongside said exit side pair of conveyors so that when it is rotated toward the side of said article said roller comes into contact with said article, and a pair of guide rails each being arranged so that the vertical distance between them are gradually decreased towards the direction of the movement of said article. I 

1. A method for wrapping an article, comprising the steps of compressing the article, advancing said article in a compressed state toward a sheet of thermoplastic resin film which is tightly spread in front of said article transverse to the direction of movement of said article, wrapping said article with said film from its forward end toward its rear end in connection with its movement as said article continues advancing, folding said film on the rear end surface of said article, fuse welding together the folded portions of said film at the rear end surface of said article, severing said film at the fuse-welded portion, moving the edge portions of said film projecting transversely beyond the sides of said article forward at a faster rate than said article as said article is further moved forwardly to stretch said edges, folding said stretched edges together, and fuse welding the stretched edges together.
 2. A machine for wrapping an article comprising a pair of spaced-apart feed conveyor means for advancing an article to be wrapped while it is subjected to compression between the spaced pair of feed conveyor means, means for feeding webs of thermoplastic resin film so that a sheet of said film is disposed perpendicular to the movement of said article and is caused to be fed from said web feed means when the forward end surface of said moving article comes into contact with said film, fuse-welding means arranged forwardly of said feed conveyor means for fuse welding said film, severing means arranged forwardly of said feed conveyor means for severing said fuse welded film, a pair of spaced-apart transferring conveyor means arranged forwardly of said fuse welding and severing means to advance said article in a compressed state, means operatively associated with said pair of feed conveyor means and with said pair of trAnsferring conveyor means to automatically adjust the space between the pair of transferring conveyor means in response to changes in the space between the feed conveyor means, and folding means arranged alongside said transferring conveyor means for folding the edges of said film projecting transversely beyond said article on said side surface thereof as the article is further advanced.
 3. A machine for wrapping an article comprising feed means for advancing an article to be wrapped while it is subjected to compression, means for feeding webs of thermoplastic resin film so that a sheet of said film is disposed perpendicular to the movement of said article and is caused to be fed from said means when the forward end surface of said moving article comes into contact with said film, fuse-welding means arranged forwardly of said feed means for fuse welding said film, severing means arranged forwardly of said feed means for severing said fuse-welded film, transferring means arranged forwardly of said fuse welding and severing means to advance said article in a compressed state, folding means arranged alongside said transferring means for folding the edges of said film projecting transversely beyond said article on each side surface thereof as the article is further advanced, said feed means comprising an entrance side pair of conveyors disposed one above the other, means for adjusting the distance between said entrance pair of conveyors, said transferring means comprising an exit side pair of conveyors disposed one above the other, means for adjusting the distance between said exit side pair of conveyors in cooperation with the adjustment of the distance between said entrance side pair of conveyors, an inserting lever on each side of said exit side pair of conveyors, means connected to each said inserting lever for introducing said inserting lever into a space defined by the forward end portion of said thermoplastic resin film, the side surface of said article and the edges of said film projecting transversely beyond said article as said film is caused to be fed from said means upon the advancement of said article, and means for moving said inserting lever at a slightly higher velocity than that of said article.
 4. A machine for wrapping an article as set forth in claim 2, wherein said adjusting means comprises driving mechanisms for cooperatively adjusting respective distances between said entrance side pair of conveyors and said exit side pair of conveyors, said driving mechanisms including dogs mounted on one of said entrance side pair of conveyors for movement therewith and limit switches on one of said exit side pair of conveyors at positions corresponding to the positions of said dogs so that the switches are actuated by respective said dogs when said conveyor provided with said dogs moves up or down, whereby said dogs and said limit switches cooperate to detect the movement of said conveyor having said dogs and to cause the movement of said conveyor having said limit switches in the same direction as that of said conveyor having dogs.
 5. A machine for wrapping an article as set forth in claim 3, wherein said inserting lever is pivotally mounted on a slide member which is slidable on a rail disposed parallel to said exit side pair of conveyors, said means connected to said inserting lever for introducing said inserting lever into said space comprising a projection secured to said lever and a guide lever rotatably mounted on said inserting lever axis, said guide lever, engaging and riding on a cam surface provided on said rail as said slide member is moved in association with the movement of said article to cause said inserting lever to be introduced into said space, and means for moving said slide member at a velocity slightly higher than that of said article.
 6. A machine for wrapping an article as set forth in claim 3, wherein said inserting lever is mounted on a sliding member, said sliding member being mounted on a fixed guide rod and a movable guide rod, said guide rods being parallel with each other and supported between a bracket and a driving box, said bracket and said driving box each mounted on a frame alongside said exit side pair of conveyors, pulleys mounted on said bracket under said driving box, an endless rope reeved on said pulleys, said endless rope passing through said sliding member at its upper and lower portions, each of said upper and lower portions provided with a clamp and a chuck mechanism cooperating to grasp a portion of said rope alternately when either one of said clamp and chuck mechanisms is engaged, said clamp and chuck mechanisms being actuated through said movable guide rod when it is engaged by said article as it is moved along by said exit side pair of conveyors.
 7. A machine for wrapping an article comprising feed means for advancing an article to be wrapped while it is subjected to compression, means for feeding webs of thermoplastic resin film so that a sheet of said film is disposed perpendicular to the movement of said article and is caused to be fed from said means when the forward end surface of said moving article comes into contact with said film, fuse welding means arranged forwardly of said feed means for fuse welding said film, severing means arranged forwardly of said feed means for severing said fuse welded film, transferring means arranged forwardly of said fuse welding and severing means to advance said article in a compressed state, folding means arranged alongside said transferring means for folding the edges of said film projecting transversely beyond said article on each side surface thereof as the article is further advanced, said feed means comprising an entrance side pair of conveyors disposed one above the other, means for adjusting the distance between said entrance pair of conveyors, said transferring means comprising an exit side pair of conveyors disposed one above the other, means for adjusting the distance between said exit side pair of conveyors in cooperation with the adjustment of the distance between said entrance side pair of conveyors, said folding means comprising a pair of rollers each rotatably disposed at each side of said exit side pair of conveyors adjacent its exit end, a pair of rollers each rotatably mounted on one end of an arm adjacent the entrance end of said exit side pair of conveyors, said arm pivotally mounted at its other end on a frame alongside said exit side pair of conveyors so that when it is rotated toward the side of said article said roller comes into contact with said article, and a pair of guide rails each being arranged so that the vertical distance between them are gradually decreased towards the direction of the movement of said article. 